POWER SUPPLY SYSTEM

The power supply system includes a high-voltage battery connected to the drive device by a high-voltage system power line, a low-voltage battery connected to the auxiliary device by a low-voltage system power line, a main power converter connected to the high-voltage system power line and the low-voltage system power line, and a bidirectional charger connected to the external power side and the high-voltage system power line for charging the high-voltage battery and supplying the voltage of the high-voltage battery to an external electric load. When a failure is detected in the main power converter, the charger power converter is controlled so as to step down the power of the high-voltage system power line by the charger power converter and supply the power to the low-voltage system power line.